The invention relates to an apparatus for the determination of at least one interface of a slag layer on top of a molten metal, the apparatus having a carrier tube, on whose one end a measuring head is arranged, which measuring head has a preferably cylindrical body fixed within the carrier tube and whose end face faces away from the carrier tube.
Similar apparatuses are known from German published patent application DE 36 41 987 A1, for example. Here, an induction coil is arranged within a carrier tube, in order to determine the slag height on top of steel melt. From German Patent DE 44 02 463 C2 it is known to use a first electromagnetic sensor together with a second sensor for ascertaining the slag thickness. Furthermore, a sensor for the measurement of the slag thickness is known from International application publication No. WO 98/14755, in which the slag is measured with the aid of an optical fiber. According to German Patent DE 31 33 182 C1, a metal bath level is determined with the aid of a short circuit caused by a voltage change. Japanese patent application publication JP 2003049215 discloses the determination of the slag thickness by using two induction coils. A further device for measuring the thickness of a slag layer is known from International application publication No. WO 03/060432 A1. Here, the use of an expendable electronic measuring component within the sensor is described, wherein the signals from the sensor are transmitted wirelessly to an analyzing station. It is also known to determine the slag thickness by means of microwaves (U.S. Pat. No. 5,182,565).